EVAL-AD7877EBZ Analog Devices Inc, EVAL-AD7877EBZ Datasheet - Page 7

• Manufacturer Part Number: EVAL-AD7877EBZ
• Description: BOARD EVALUATION FOR AD7877
• Manufacturer: Analog Devices Inc

Specifications of EVAL-AD7877EBZ

• Main Purpose: Interface, Touch Screen Controller
• Embedded: No
• Utilized Ic / Part: AD7877
• Primary Attributes: 4-Wire Resistive Touch Screen Controller, SPI Interface, On-Chip: Temp Sensor, Voltage Reference, 8-Bit DAC
• Secondary Attributes: USB GUI, LCD Noise Reduction Feature, 2.7 ~ 5.25 V, Wake Up on Touch Feature
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

VISUAL DISPLAY SCREEN
Clicking on the Visual Display tab will bring the user to the
screen shown in Figure 6. Values measured by the AD7877 can
be graphed on this screen.
Selecting a Channel Measurement to Display
To select the measurement to be graphed, select one of the
channels from the list. The selected channel value will be
displayed on the left of the screen, along with the channel high
and low limits, if there are any. The limits may be changed
by dragging the limit bars up or down. The new limits are
automatically written to the relevant AD7877 registers by the
evaluation software.
The AUX1, BAT1, BAT2, and Temp1 channels all have upper
and lower limits. Also displayed next to these channels in the list
is an ALERT button. If the button is green, the channel’s mea-
sured value is within its limits. If the button is red, the channel’s
measured value is outside its limits and is causing the ALERT
interrupt to assert.
REV. Sp0
Figure 6. Visual Display Screen
–7–
In Figure 6, the Temp1 measurement is selected. The bar graph
shows the value in the Temp1 register. The upper limit in Figure 6
is set to 47.38°C, while the lower limit is set to 26.74°C. These
limits can be changed by clicking and dragging on the limit bars. In
Figure 6, the temperature breaches the lower temperature limit
and so an ALERT interrupt is triggered. The ALERT interrupt
indicator button long side Temp1 has changed from green to red
to reflect this.
Graphing a Measurement
On the right of the Visual Display screen is a graphing area.
What is graphed here depends on which channel is selected. If
any of the following is the selected channel, then all are graphed
in the graphing area: AUX1, AUX2, AUX3, BAT1, and BAT2.
If any of the touch screen measurement channels (X+, Y+, Y–,
or Z1) are selected, then all four channels are graphed. If either
of the temperature measurement channels is selected, then both
channels are displayed in the graphing area. Graphing more
than one channel at a time makes it easy for the user to compare
and contrast channel measurements.
In Figure 7, the Y+ measurement is selected. In the graphing
window, the four touch screen measurements are graphed.
EVAL-AD7877